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Ship trials in the virtual world

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A vessel’s hydrodynamic performance is an important factor in its fuel efficiency and life-cycle costs. Understanding the characteristics that shape performance can result in a competitive advantage during the conceptual design and bidding phase of a newbuilding project, or during the purchasing process and charter party negotiations for vessels in service.

Published:12 October 2017

Keywords:
Maritime

Today, we have several different options for assessing hydrodynamic performance. Empirical benchmarking, by searching databases for vessels with similar principle parameters, can be a quick and inexpensive way to assess a design. But the results will only reflect general trends rather than give accurate predictions and are of limited use for unusual, innovative designs. Model tests provide a much more detailed assessment of the hydrodynamic performance of a vessel. But with a typical lead time of about ten weeks, they can take too long for projects in the initial design and tender phase as well as be very costly. Additionally, while results from the same facility can be consistent across designs, comparing the results of different facilities can be challenging.

As computational fluid dynamics (CFD) simulation technology has matured, it has become a viable alternative to traditional model basin tests, also because it reduces lead time and costs. However, the computer resources and expert know-how to design and carry out such tests are still not widespread. At the same time, the varying assumptions and simulation parameters used by yards and design offices make reliable comparison and benchmarking nearly impossible.

Speed power curves in web-based report

Choosing the most efficient design option for newbuilding or retrofit projects

The new Virtual Trial application from DNV GL removes the need for expert support by streamlining and automating the CFD simulation process. Users can upload individual vessel hull forms, run simulations with pre-set parameters and then easily compare their results against the results of similar vessels. Whether for a newbuilding or retrofit project, Virtual Trial reduces the barriers to full-scale CFD simulation testing and comparative benchmarking.

Virtual trials can be launched in complete anonymity, from anywhere, at any time, by simply uploading the hull geometry file and defining the operating profile. Then, without the need for any CFD-specific input, users can conduct fully automated, full-scale RANSE (Reynolds-averaged Navier-Stokes equations) VoF (Volume of Fluid) CFD simulations on the resistance and propulsion of their vessel. The results are available within one week, in a Web-based report showing the CFD results and hull lines in 3D to enable users to gain more insight into the flow details.

3D viewer to investigate flow details

Typical use cases

A typical use case might be design offices and shipyards wanting to analyze and benchmark different hull options during the conceptual design phase. During the later design phase, they could track the influence of design changes on the vessel’s hydrodynamic performance, ensuring that contractual requirements are still achievable.

The standardized CFD setup also lets shipyards and designers see where they could improve their designs by comparing them against anonymized state-of-the-art designs from the Virtual Trial database.

Using Virtual Trial on My DNV GL will also let ship owners compare design proposals from different yards or design offices during the bidding process. Competing designs can be uploaded to Virtual Trial by the designers themselves, to ensure that the hull lines stay confidential. The ship owner can then be granted access to the results, providing him or her with a consistent and impartial assessment of the designs at a fraction of the cost and lead time of model tests.

For vessels in service, Virtual Trial results could act as a performance certificate to show potential charterers that the vessel has undergone a transparent efficiency assessment. Even with advanced performance monitoring solutions, it can be difficult to predict the performance or the fuel consumption for a different operating profile. But with the Virtual Trial app, the owner could simulate the intended operating parameters and provide a tailored performance assessment to the potential charterer within a week.

Standardized report format

Virtual Trial’s standardized report format could also become an industry-accepted reference for comparison and benchmarking. Ship designs can be compared against each other within a set frame of reference, even if the projects are submitted from different parties, making performance predictions more transparent and reliable. Virtual Trial lets customers take control of their data, benefit from industry-wide benchmarking capabilities, and enhance their market competitiveness.